In a general turbine (for example, a steam turbine), a rotor which is a rotary shaft is rotatably supported by a casing, a rotor blade is installed on the outer peripheral section of the rotor, a stator blade is installed on the inner wall of the casing, and a plurality of the rotor blades and a plurality of the stator blades are alternately provided in a steam passage. Moreover, the rotor blades and the rotor are rotatably driven while steam flows into the steam passage.
In this steam turbine, the rotor blade includes a blade base section which is fixed to a rotor disk of the rotor, a platform which is integrally formed with the blade base section, a blade section in which the base end section is joined to the platform and extends to the tip section side, and a shroud which is connected to the tip section of the blade section. In addition, the rotor blades are fixed so that a plurality of the base end sections are arranged along the peripheral direction on the outer peripheral section of the rotor disk, and are annularly disposed around the axial direction of the rotor so that the shrouds of the tip section come into contact with each other.
As a method for manufacturing the steam turbine rotor blade, for example, in PTL 1, a method for manufacturing a turbine blade (rotor blade) made of a titanium alloy capable of withstanding erosion (corrosion) and having excellent reliability is disclosed. The method for manufacturing the blade includes a forging step of forming the turbine blade made of the titanium alloy by hot-forging, a step of more rapidly cooling the tip side of the blade leading edge section of the turbine blade including a cover formed by the hot-forging than a blade main body, and a step of heat-treating the turbine blade after the cooling.